LATROBE, Pa. (93-7 THE FAN/AP) — The routine of another last-week-of-training-camp practice was disrupted in a potentially major way when the Steelers saw both of their first-string running backs end up on the sidelines.

First, it was veteran Isaac Redman who stayed on the ground for a while, but what fell him doesn’t appear to be serious.

“Yeah, just a little stinger,” Redman told 93.7 The Fan’s Jim Colony while walking off the field. “Everything’s good.”

The other running back listed as a co-starter on this week’s depth chart wasn’t quite as lucky.

Rookie Le’Veon Bell went down in a subsequent 11-on-11 period and stayed down for about five minutes as trainer John Norwig and staff examined his left knee. Bell did not go to the locker room immediately, and he spent the rest of practice standing behind the offense.

Head coach Mike Tomlin didn’t have much to add, saying only that Bell “re-aggravated [his] knee and will be evaluated shortly.”

Bell was eventually helped off the field and watched the final hour of practice with his knee heavily wrapped. He was walking under his own power but favoring his knee. He removed the wrap at the end of practice, slowly walked to a golf cart, and was taken off the field.

Bell was not available to the media.

Tomlin has run a relatively physical camp with more live practices that feature more contact than he has in recent years. But the drill in which Bell was injured was not a live one.

Bell was held out of Pittsburgh’s preseason opener against the New York Giants on Saturday because of the sore right knee, a decision Tomlin said was “a precaution.” He missed a practice a week earlier and was limited in others over the past two weeks.

In his stead, Pitt product LaRod Stephens-Howling ran for a team-high 40 of the Steelers’ 94 rushing yards in their 18-13 loss to the visiting Giants last Saturday. Redman carried just twice for seven yards.

Otherwise, Tomlin was generally happy with the pace of practice, but was miffed by several botched center-quarterback exchanges.

“That can put a stain on a practice,” said Tomlin. “We’ve got to be better than that.”

Former Pitt and Franklin Regional standout John Malecki is listed as back-up center, but is getting more work at guard this week since, according to Malecki, coaches want to test the versatility of Kelvin Beachum at that spot.

The Steelers (0-1) break camp Saturday and continue their preseason against the Redskins (1-0) at FedExField Monday night at 8:00.